DESCRIPTION (Applicant's Abstract): Loneliness and stress may disrupt neuroendocrine function, accelerating reproductive aging in humans as it does in rats. My initial study indicates that, as young as 35 to 49 years of age, Blacks have more prolonged menstrual cycles than do Whites (when measured as either a menstrual cycle or the time between subsequent preovulatory surges of Luteinizing Hormone (LH). Using a newly developed technique for pinpointing the onset of the preovulatory LH surge, this dissertation project will be the first to determine in African American women, whether prolonged cycles at this age are caused by increased follicular phase lengths, luteal phase lengths or duration of menses. Specifically, this project will test the hypotheses that: a) this pattern of ovarian cycle prolongation will replicate in a larger population of African American women. b) that prolonged cycles result from o prolonged follicular phase and not from a prolonged luteal phase or menses. c) that cycle prolongation is only found in a sub-population of Blacks, particularly those that are lonely or stressed. In order to ensure variability in these psychological states, I will recruit women from both high and low SES as well as women who are embedded to various degrees within the church community. Because dissertation projects are limited in time, I will begin this line of research with an age-cohort design. Menstrual cycle, hormonal, and psychosocial data will be collected prospectively from sixty 30 to 49 year-old Black women throughout 2 ovarian cycles. This age-cohort project will serve as a nucleus for future longitudinal studies. Prolonged follicular phases are likely to result in prolonged exposure to unopposed estrogen within a given cycle. Unopposed estrogen is known to damage the neuroendocrine system in rats and, in humans, is associated with increased risk for estrogen-related diseases later in life, such as breast cancer. This study contributes basic information about African American women, which is needed to assess the effects of daily experiences on their mental health and risk for physical disease.